equality constraints exposed by patterns mess up constraint inference
|Reported by:||heisenbug||Owned by:|
|Type of failure:||GHC rejects valid program||Difficulty:||Unknown|
|Test Case:||Blocked By:|
When patterns bring (equality) constraints into scope, the inference mechanism for other (unrelated) constraints breaks down.
This is a new problem that appeared between
- ghc-7.7.20121025 and
I can try to track down the commit if that helps.
Testcase against HEAD attached.